Needed route for PayPalStandard PDTHandler added.

Without this route the following site is displayed.
![sitenotfound](https://cloud.githubusercontent.com/assets/2790090/4781435/f5165ff4-5c9e-11e4-9f26-1baf67444073.PNG)

In the PayPalStandard Settings-Page the following is described.
![descriptionpaypalstandard](https://cloud.githubusercontent.com/assets/2790090/4781437/0b955096-5c9f-11e4-88a8-d0304a3ae11f.PNG)

The Handler is configured in the PayPal ReturnUrl
![paypalsettings](https://cloud.githubusercontent.com/assets/2790090/4781439/231fa04a-5c9f-11e4-807a-d3c1b6614f4e.PNG)